#列表切片取值(同字符串)
list_1 = [10, 20, 30, 40, 50, 60, 70]
print(list_1[:])                      # [10, 20, 30, 40, 50, 60, 70]
print(list_1[0:3])                    # [10, 20, 30]
print(list_1[-3:-1])                  # [50, 60]
print(list_1[-3:])                    # [50, 60, 70]
 #步长
print(list_1[1:6])                    # [20, 30, 40, 50, 60]
print(list_1[1:6:2])                  # [20, 40, 60]
print(list_1[-6:-1:2])                # [20, 40, 60]
print(list_1[::-1])                   # [70, 60, 50, 40, 30, 20, 10]